Dual clutch arrangement

ABSTRACT

A dual clutch arrangement for a dual clutch transmission for motor vehicles, having a first and a second friction clutch which are each fluidically actuable. A first piston arrangement serves to actuate the first friction clutch and has a first piston, a first piston space and a first centrifugal force equalizing space. A second piston arrangement serves to actuate the second friction clutch and has a second piston, a second piston space and a second centrifugal force equalizing space. The piston spaces and the centrifugal force equalizing spaces are situated in each case on opposite sides of the associated piston and are connected by means of feed lines to a valve arrangement.

BACKGROUND OF THE INVENTION

The present invention relates to a dual clutch arrangement for a dualclutch transmission for motor vehicles, having a first and a secondfriction clutch which are each fluidically actuable, a first pistonarrangement which serves to actuate the first friction clutch and has afirst piston, a first piston space and a first centrifugal forceequalizing space, a second piston arrangement which serves to actuatethe second friction clutch and has a second piston, a second pistonspace and a second centrifugal force equalizing space, with the pistonspaces and the centrifugal force equalizing spaces being situated ineach case on opposite sides of the associated piston and being connectedby means of feed lines to a valve arrangement.

A dual clutch arrangement of said type is generally known.

Dual clutch transmissions have a dual clutch arrangement and two partialtransmissions. The partial transmissions are generally designed aslayshaft transmissions. Here, one of the partial transmissions isassigned to the even gear stages, and the other partial transmission isassigned to the odd gear stages.

It is consequently possible, by means of overlapping actuation of thetwo clutches of the dual clutch arrangement, to carry out a gearshiftwithout an interruption in tractive force.

Said type of dual clutch transmission is suitable for motor vehicles, inparticular for passenger vehicles.

Nowadays, fluidically operated friction clutches, for examplewet-running multiplate clutches, are generally used in dual clutcharrangements.

It is often preferable here, in order to attain a short axial design,for the two dual clutches to be nested one inside the other radially,with one friction clutch being situated radially at the inside and theother being situated radially at the outside.

In order to supply fluid, in particular hydraulic oil, to the frictionclutches, it is known to provide a rotary leadthrough with a spigotsection onto which is placed a common hub of the two dual clutches.

Here, in a known dual clutch arrangement, in each case four ducts areprovided on the rotary leadthrough and on the hub, with two of the ductsbeing assigned to the two piston spaces, and with the other two ductsbeing assigned to the two centrifugal force equalizing spaces.

Here, the duct for the first piston space is situated axially at oneend. Adjacent thereto is a duct for the first centrifugal forceequalizing space. Adjacent thereto is in turn a duct for the secondpiston space, and arranged at the axially other end is a duct for thesecond centrifugal force equalizing space.

BRIEF SUMMARY OF THE INVENTION

It is the object of the present invention to specify an improved dualclutch arrangement.

Said object is achieved in the dual clutch arrangement specified in theintroduction in that the centrifugal force equalizing spaces areconnected to the valve arrangement by means of a common line.

In a second aspect of the present invention, the object is achieved inthe dual clutch specified in the introduction in that the frictionclutches are embodied as radially nested multiplate clutches and have ineach case one inner plate carrier and one outer plate carrier, with theinput member of the radially outer multiplate clutch being the outerplate carrier and with the input member of the radially inner clutchbeing the inner plate carrier.

It is possible by means of the measures as per the first aspect of theinvention to provide an axially more compact dual clutch arrangementoverall, in particular since fewer feed lines to the piston spaces andfluid equalizing spaces are required for introducing fluid. There isalso a resulting weight advantage.

With the dual clutch arrangement as per the second aspect of the presentinvention, it is likewise possible to achieve a small installationlength and a resulting weight advantage.

In the dual clutch arrangement according to the present invention, it isadvantageous if the friction clutches have in each case one inputmember, with the input members being mounted on a hub and with the hubbeing rotationally fixedly connected to a drive input shaft.

Said measure generally permits an axially compact construction of thedual clutch arrangement.

Here, it is particularly advantageous if the drive input shaft isconnected to the hub by means of a cage which radially surrounds thefriction clutches.

It is advantageously possible by means of said measure to provide thatthe drive output members of the friction clutches are guided radiallypast the hub in the vicinity of the drive input shaft.

According to a further preferred embodiment, the hub is mounted on aspigot section, which is fixed to the housing, of a rotary leadthrough.

It is hereby possible to provide that the friction clutches are suppliedwith fluid for their operation via the rotary leadthrough and the hub.

It is particularly advantageous here if the hub has radial ducts inorder to supply the friction clutches with fluid.

It is also advantageous here if the hub has at least two radialactuating ducts for actuating the two friction clutches. In the presentcontext, the term “radial duct” is to be understood in a broad sense. Inthe illustration of the radial ducts and of the associated rotaryleadthrough, a longitudinal section view is generally assumed in which,thus, in each case only one radial duct or one projection of radialducts can be seen. It is however self-evident that a radial duct can forexample also be understood as a plurality of individual ducts, forexample bores, which are distributed in the peripheral direction. Anindividual radial duct is also to be understood within the context ofthe present invention as when two individual ducts which are offset inthe peripheral direction are connected to one single annular duct of arotary leadthrough, but radially outwardly deviate from one another inthe axial direction.

The rotary leadthrough preferably has an annular duct which forms thecommon line to the two centrifugal force equalizing spaces.

Here, it is particularly advantageous if the annular duct is arranged inthe axial direction between the two actuating radial ducts.

It is possible by means of said measure to connect the annular duct tothe two centrifugal force equalizing spaces, in particular when thelatter are arranged adjacent to one another in the axial directionbetween the two piston spaces.

According to a further preferred embodiment, the hub has at least onefirst radial auxiliary duct, which is connected to the first centrifugalforce equalizing space, and at least one second radial auxiliary ductwhich is connected to the second centrifugal force equalizing space,with the radial auxiliary ducts being connected radially at the insideto the annular duct.

Here, the radial auxiliary ducts can on the one hand be composed in eachcase of radially outwardly branching, in each case interconnected ducts.It is however preferable for the first radial auxiliary duct and thesecond radial auxiliary duct to be offset relative to one another in theperipheral direction. Only one individual radial duct can be seen in aprojection in the peripheral direction, so that in the present case, forsimplicity, reference is at some points made to “one” radial auxiliaryduct.

Here, it is also particularly advantageous for an input member of one ofthe friction clutches to be connected to the hub in a region between thetwo radial auxiliary ducts.

In this way, the input member of said friction clutch can be used as aseparating member between the two centrifugal force equalizing spaces.The friction clutch whose input member is connected to the hub in thisway is preferably a radially inner friction clutch.

According to a further preferred embodiment, the annular duct serves tosupply at least one of the friction clutches with cooling fluid.

According to a further preferred embodiment, the centrifugal forceequalizing spaces are fluidically connected to one another.

The centrifugal force equalizing spaces are generally always in anunpressurized state, that is to say are supplied with fluid which is notpressurized. If, for example, a clutch is actuated by introducingpressurized fluid into the associated piston space, fluid is forced outof the associated centrifugal force equalizing space. This is easier toprovide if the two centrifugal force equalizing spaces are fluidicallyconnected to one another. There is in particular no requirement forcomplicated duct arrangements in the rotary leadthrough and/or in thehub.

It is however generally also conceivable, in the case of the adjacentcentrifugal force equalizing spaces, for the latter to be fluidicallyconnected to one another for example by means of openings in aseparating member (such as an input member of a radially inner frictionclutch).

According to an embodiment which is preferable overall, the frictionclutches are embodied as radially nested multiplate clutches, ormultiplate clutches which are arranged one inside the other, and have ineach case one inner plate carrier and one outer plate carrier.

In said embodiment, it is particularly advantageous for the input memberof the radially outer multiplate clutch to be its outer plate carrierand for the input member of the radially inner clutch to be its innerplate carrier.

In this way, it is provided in a structurally simple manner that thedual clutch arrangement can be of an axially short overall design.

It is self-evident that the features stated above and the features yetto be explained in the following can be used not only in therespectively specified combination but also in other combinations orindividually without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are illustrated in the drawingand are explained in more detail in the following description. In thedrawing:

FIG. 1 shows a schematic longitudinal section view of a dual clutcharrangement (half-section view of a substantially rotationallysymmetrical arrangement) as per one embodiment of the present invention,in conjunction with associated components of a dual clutch transmission;and

FIG. 2 shows a longitudinal section of a hub of the dual clutcharrangement from FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, a drivetrain for a motor vehicle is denoted generally by 10.

The drivetrain 10 has a schematically indicated internal combustionengine 12 whose output is connected to a dual clutch transmission 14.

The drivetrain 10 is particularly suitable for motor vehicles. The motorfor driving the motor vehicle can be the internal combustion engine 12or any other desired drive motor such as for example an electric drive,a hybrid drive or the like.

The dual clutch transmission 14 contains a multistep transmission,denoted schematically in the figure by 16, which is designed as alayshaft transmission and contains two partial transmissions.

In addition, the dual clutch transmission 14 has a dual clutcharrangement 20 whose input is connected to the output of the internalcombustion engine 12 and which is connected at the output side to themultistep transmission 16.

More precisely, the dual clutch transmission 20 has an input shaft 22which can be rotationally fixedly connected by means of a toothing orthe like to the drive output shaft of the internal combustion engine 12.

The dual clutch arrangement 20 also has a first output shaft 24 in theform of a solid shaft which is connected to a first partial transmissionof the multistep transmission 16. In addition, the dual clutcharrangement 20 has a second output shaft 26 in the form of a hollowshaft which is connected to the second partial transmission. The shafts24, 26 are arranged concentrically with respect to one another.

The dual clutch arrangement 20 has a first friction clutch 28 which isdesigned to connect the input shaft 22 to the first output shaft 24, andhas a second friction clutch 30 which is designed to connect the inputshaft 22 to the second output shaft 26.

The two friction clutches 28, 30 are radially nested, with the firstfriction clutch 28 being arranged radially at the outside and with thesecond friction clutch 30 being arranged, concentrically with respectthereto, radially at the inside.

The two friction clutches 28, 30 are held in a cage 32 which isconnected to the input shaft 22. More precisely, the cage 32 has a firstcage section 34 which is connected to the input shaft 22 and extendsradially outward from the latter. In addition, the cage 32 has a secondcage section 36 which is rotationally fixedly connected to the firstcage section 34 and has a cylindrical section, in the form of an outerplate carrier 38 of the first friction clutch 28, and a radiallyinwardly extending partial section.

An inner plate carrier 40 of the first friction clutch 28 is connectedto a first basket 42 which runs directly adjacent to the first cagesection 34 and is connected by means of a first toothing 44 to the firstoutput shaft 24.

The second friction clutch 30 has an outer plate carrier 46 which isconnected to a second basket 48. The second basket 48 runs in the directvicinity of the first basket 42 and is connected by means of a secondtoothing 50 to the second output shaft 26 (the hollow shaft).

As is schematically indicated in the figure, axial bearings can bearranged between the first cage section 34 and the first basket 42 andbetween the first basket 42 and the second basket 48.

In the figure, 60 denotes a clutch carrier which is mounted so as to befixed to the housing, that is to say does not rotate. In addition,schematically illustrated at 58 is a valve arrangement or a hydrauliccontrol arrangement, by means of which the dual clutch arrangement canbe operated.

Fastened to the clutch carrier 60 is a rotary leadthrough arrangement 62which has an axially projecting hollow spigot section 64 which isarranged concentrically around the two output shafts 24, 26. The spigotsection 64 extends axially from the side of the second cage section 36towards and almost as far as the second basket 48 which is connected tothe second output shaft 26. Here, the spigot section 64 is situatedradially within the two friction clutches 28, 30.

A hub 66 is rotatably mounted on the spigot section 64 of the rotaryleadthrough arrangement 62. The figure shows two bearings, by means ofwhich the hub 66 is rotatably mounted on the spigot section 64 of therotary leadthrough arrangement 62.

The second cage section 36 is rigidly connected to the hub 66, so thatthe hub 66 forms an input member of the dual clutch arrangement 20 androtates at the rotational speed of the attached motor 12.

An inner plate carrier 68 of the second friction clutch 30 is fixed tothe hub 66.

Between the inner plate carrier 68 and the second cage section 36, afirst piston 70 of the first friction clutch 28 is mounted so as to beaxially displaceable relative to the hub 66. The piston 70 is ofdisk-like design and extends from the hub 66 radially outward as far asthe first friction clutch 28.

A first piston space 72 is formed between the second cage section 36 andthe first piston 70. The first piston space 72 is connected by means ofthe rotary leadthrough arrangement 62 and the clutch carrier 60 to thevalve arrangement 58. By supplying fluid (generally hydraulic fluid suchas for example ATF oil) into the first piston space 72 (via the firstradial actuating duct 74, see below), the first piston 70 is displacedaxially relative to the second cage section 36 and presses the plates ofthe first friction clutch 28 together, so that said plates come intofrictional engagement in order to thereby close the first frictionclutch 28 and to connect the input shaft 22 to the first output shaft24.

The transition from the open state into the closed state of the firstfriction clutch 28 can take place in a controlled fashion in such a waythat a suitable slip phase occurs in order to thereby permit jerk-freestarting and gearshifts, respectively.

For the purpose of supplying hydraulic fluid into the first piston space72, a first radial actuating duct 74 (formed for example by means of aplurality of bores which are offset in the peripheral direction) isprovided in the hub 66, which first radial actuating duct 74 connectsthe first piston space 72 to a corresponding first annular duct (notdenoted in any more detail in the figure) of the spigot section 64, withthe first annular duct in turn being connected, by means of suitableducts in the rotary leadthrough arrangement 62, to the clutch carrier 60or to the valve arrangement 58.

Also formed on the inner plate carrier 68 is a web (not denoted in anymore detail), against which are supported a plurality of first returnsprings 76 which are arranged so as to be distributed uniformly aboutthe periphery. The actuation of the first piston 70 accordingly takesplace counter to the force of the first return springs 76.

A first centrifugal force equalizing space 78 is provided between thepiston 70 and the inner plate carrier 68 of the second friction clutch30.

The centrifugal force equalizing space 78 has the function of generatinga counterforce to a clutch actuating force which is generated by thecentrifugal force and is generated in the associated first piston space72.

At high rotational speeds in particular, the hydraulic fluid which ispresent in the first piston space 72 is pushed outward in such a waythat ultimately a force is exerted on the piston in the direction ofactuation of the first friction clutch 28. Said force, in the manner ofan interference force, consequently counteracts a return force which isexerted by the return springs 76 as the first friction clutch 28 opens.In order to equalize said “interference force”, hydraulic fluid isallowed to flow, unpressurized, into the opposite centrifugal forceequalizing space 78. There, as a result of the centrifugal force, acounter-force in the opening direction of the first friction clutch 28is generated which counteracts said “interference force” and cancels outthe latter.

For this purpose, the first centrifugal force equalizing space 78 isconnected by means of a first radial auxiliary duct 80 to a secondannular duct 82 on the spigot section 64, with the second annular duct82 in turn being connected by means of corresponding ducts or lines inthe rotary leadthrough arrangement 62 to the valve arrangement 58.

A second centrifugal force equalizing space 86 is set up at the otherside of the inner plate carrier 68. Said centrifugal force equalizingspace 86 is connected by means of a second radial auxiliary duct 84 tothe second annular duct 82 of the spigot section 64.

The two centrifugal force equalizing spaces 78, 86 are consequentlyadjacent to one another and separated from one another by the innerplate carrier 68 of the second friction clutch 30.

The second centrifugal force equalizing space 86 is delimited at theaxially other side by a second piston 90 which is likewise mounted so asto be displaceable in the axial direction relative to the hub 66.

A support member 89 is fastened to the hub 66. Said support member 89extends outward in the radial direction axially between the secondpiston 90 and the second basket 48. A second piston space 92 is set upbetween the support member 89 and the second piston 90. The secondpiston space 92 is connected by means of a second radial actuating duct94 to a third annular duct on the spigot section 64. The second pistonspace 92 is connected to the valve arrangement 58 by means of said thirdannular duct.

Furthermore, second return springs 96 are arranged in the secondcentrifugal force equalizing space 86, which second return springs 96are supported against a bearing element 88. The bearing element 88 is inturn supported against a free end of the inner plate carrier 68 or isfixed thereto. The bearing element 88 also serves to delimit the secondcentrifugal force equalizing space 86 by means of a seal between thebearing element 88 and the second piston 90.

The functioning of the second friction clutch 30 corresponds to that ofthe first friction clutch 28, merely with the actuating direction beingaligned in the opposite direction. While the first piston 70 is arrangedat the one side of the two friction clutches 28, 30, the second piston90 is arranged at the opposite side. The second piston 90 is likewiseembodied as a disk-like element, which is mounted on the hub 66 in anaxially central region of the second friction clutch 30. The secondpiston 90 extends radially outward around the second friction clutch 30from said axially central region. The second centrifugal forceequalizing space 86 is hereby arranged substantially radially within thesecond friction clutch 30. The second return springs 96 are alsoarranged radially within the second friction clutch 30.

As a result of said measure, the dual clutch arrangement 20 can bedesigned overall to be particularly compact in the axial direction.

This is also facilitated in that the two centrifugal force equalizingspaces 78, 86 are arranged adjacent to one another and can be connectedto the valve arrangement 58 by means of the second annular duct 82 onthe spigot section 64 of the rotary leadthrough arrangement 62, that isto say can ultimately be supplied with unpressurized hydraulic fluid viaone single duct (a common line).

It is also possible for the friction clutches 28, 30 to be supplied withcooling fluid via the second annular duct 82 or via the radial auxiliaryducts which are arranged so as to be offset in the peripheral direction.Said cooling fluid passes out, for example through bores in the platecarriers, radially outward as a result of the centrifugal forces, andcools the two friction clutches 28, 30. The fluid returns from there(generally via a cooler).

The return springs 76, 96 are illustrated in the figure as coil springs.Plate springs could however also be used instead.

It is particularly preferable that only three peripheral grooves(annular ducts) which are offset in the axial direction are required onthe spigot section 64 of the rotary leadthrough arrangement 62 forfeeding hydraulic fluid to the dual clutch arrangement 20. This alsoresults in a short axial installation length and a weight advantage.

In order to actuate the friction clutches 28, 30, hydraulic fluid at apressure in the region of for example 15 bar is introduced in each caseinto the respective piston spaces 72 and 92.

Although, in the figure, the hub 66 is illustrated with in each case onefirst radial actuating duct 74, one third radial actuating duct 94 andwith two radial auxiliary ducts 80, 84, it is self-evident thatcorresponding ducts or bores can be arranged so as to be distributedabout the periphery of the hub 66.

The hub 66 is illustrated in a longitudinal section view in FIG. 2. Itcan be seen here that the “radial ducts” 74, 80, 84, 94 can in each casebe composed of a plurality of peripherally distributed bores. Here, thebores of the ducts 80, 84 are provided so as to alternate in theperipheral direction. The ducts 80, 84 open out radially at the insideinto a common line 102.

The bores of the duct 80 run radially vertically; the bores of the duct84 run radially outward at an angle.

Bores of the ducts 84, 94 of the clutch 30 open out at the outside ineach case on one axial line 101. The bores of the ducts 80, 74correspondingly open out in each case on an axial line 103 which isoffset in the peripheral direction.

1. A dual clutch arrangement for a dual clutch transmission for motorvehicles, having a first and a second friction clutch which are eachfluidically actuable, a first piston arrangement which serves to actuatethe first friction clutch and has a first piston, a first piston spaceand a first centrifugal force equalizing space, a second pistonarrangement which serves to actuate the second friction clutch and has asecond piston, a second piston space and a second centrifugal forceequalizing space, with the piston spaces and the centrifugal forceequalizing spaces being situated in each case on opposite sides of theassociated piston and being connected by means of feed lines to a valvearrangement, wherein the centrifugal force equalizing spaces areconnected to the valve arrangement by means of a common line.
 2. Thedual clutch arrangement as claimed in claim 1, wherein the frictionclutches have in each case one input member, with the input membersbeing mounted on a hub and with the hub being rotationally fixedlyconnected to a drive input shaft.
 3. The dual clutch arrangement asclaimed in claim 2, wherein the drive input shaft is connected to thehub by means of a cage which radially surrounds the friction clutches.4. The dual clutch arrangement as claimed in claim 2, wherein the hub ismounted on a spigot section, which is fixed to the housing, of a rotaryleadthrough.
 5. The dual clutch arrangement as claimed in claim 4,wherein the hub has radial ducts in order to supply the frictionclutches with fluid.
 6. The dual clutch arrangement as claimed in claim5, wherein the hub has at least two radial actuating ducts for actuatingthe friction clutches.
 7. The dual clutch arrangement as claimed inclaim 4, wherein the rotary leadthrough has an annular duct which formsthe common line to the two centrifugal force equalizing spaces.
 8. Thedual clutch arrangement as claimed in claim 7, wherein the hub has atleast one first radial auxiliary duct, which is connected to the firstcentrifugal force equalizing space, and at least one second radialauxiliary duct which is connected to the second centrifugal forceequalizing space, with the radial auxiliary ducts being connectedradially at the inside to the annular duct.
 9. The dual clutcharrangement as claimed in claim 8, wherein an input member of one of thefriction clutches is connected to the hub in a region between the tworadial auxiliary ducts.
 10. The dual clutch arrangement as claimed inclaim 6, wherein the annular duct also serves to supply at least one ofthe friction clutches with cooling fluid.
 11. The dual clutcharrangement as claimed in claim 1, wherein the centrifugal forceequalizing spaces are fluidically connected to one another.
 12. The dualclutch arrangement as claimed in claim 1, wherein the friction clutchesare embodied as radially nested multiplate clutches and have in eachcase one inner plate carrier and one outer plate carrier.
 13. The dualclutch arrangement as claimed in claim 12, wherein the input member ofthe radially outer multiplate clutch is the outer plate carrier andwherein the input member of the radially inner clutch is the inner platecarrier.
 14. A dual clutch arrangement for a dual clutch transmissionfor motor vehicles, having a first and a second friction clutch whichare each fluidically actuable, a first piston arrangement which servesto actuate the first friction clutch and has a first piston, a firstpiston space and a first centrifugal force equalizing space, a secondpiston arrangement which serves to actuate the second friction clutchand has a second piston, a second piston space and a second centrifugalforce equalizing space, with the piston spaces and the centrifugal forceequalizing spaces being situated in each case on opposite sides of theassociated piston and being connected by means of feed lines to a valvearrangement, wherein the friction clutches are embodied as radiallynested multiplate clutches and have in each case one inner plate carrierand one outer plate carrier, wherein an input member of the radiallyouter multiplate clutch is the outer plate carrier and wherein an inputmember of the radially inner clutch is the inner plate carrier.
 15. Thedual clutch arrangement as claimed in claim 14, wherein the inputmembers are mounted on a hub which is rotationally fixedly connected toa drive input shaft.
 16. The dual clutch arrangement as claimed in claim15, wherein the drive input shaft is connected to the hub by means of acage which radially surrounds the friction clutches.
 17. The dual clutcharrangement as claimed in claim 15, wherein the hub is mounted on aspigot section, which is fixed to the housing, of a rotary leadthrough.18. The dual clutch arrangement as claimed in claim 14, wherein thecentrifugal force equalizing spaces are fluidically connected to oneanother.